Question

@Mujee
@DB45

Kakak yang bisa mohon bantuannnya :)

cos 7,5derajat=....
Uraikan sampai sederhana

Answer 1

Misal A = 7,5
cos 2A = 2 cos² A - 1
cos² A = cos 2A + 1
cos² A = cos 15 + 1
cos² A = cos(45-30) + 1
cos² A = cos 45 cos 30 + sin 45 sin 30+1
cos² A = 1/2 √2 (1/2 √3) + (1/2√2)(1/2) + 1
cos² A = 1/4√6 + 1/4 √2 + 1
cos² A = 1/4 (√6+√2 + 4)
cos A = 1/2 (√6 + √2 + 4)
cos 7,5° = 1/2 (√6+√2 +4)
...